Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
Coupon (50.35 USD): BG10OFFAFF1
(CouponsFromChina.com tip: apply it in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BgcLuBofErtA10, BGFLS15, BGAFF10OFF, BGCuponation10, 4BLF, BGHONEY2110, BG10OFFAFF, BGwhielabel, BGflashlight
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Here is price history (for all/most countries) for HAIKELITE HK4S SST20 Flashlight.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).